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50 Years of Ocean Discovery: National Science Foundation 1950—2000 The Future of Ocean Chemistry in the United States1 Focus Steering Committee INTRODUCTION As part of the long-range planning process within the NSF Geosciences Directorate, the chemical oceanography community completed an examination entitled "Future of Ocean Chemistry in the U.S. (FOCUS)." There was strong consensus that the field has advanced dramatically during the past 20 years, and is poised to make fundamental new contributions in the coming decades. Chemical and biogeochemical processes in the ocean have profound implications for atmospheric chemistry, ocean biology, and (via hydrothermal processes) the evolution of the ocean crust. Chemical tracer studies underlie much of our understanding of ocean circulation, while the chemical and isotopic composition of microfossils provides a record of past ocean circulation, temperature, and climate. Chemical processes in the marine realm thus have a profound impact on key aspects of the environment while providing the tools to study other fundamental properties. A steering committee of nine scientists commissioned a series of Progress Reports, organized a workshop of forty participants held in South Carolina in January 1998, and involved the broader oceanographic community via mailings, a town meeting at the 1998 American Geophysical Union-American Society for Limnology and Oceanography Ocean Sciences meeting in San Diego, and a participatory web-site. This process summarized the status of the field via a review of recent progress, identification of major questions and future research trajectories, and assessment of the status of people and facilities in the field. The full report is published by the University Corporation for Atmospheric Research (UCAR) and available via the Consortium for Oceanographic Research and Education (CORE). This chapter summarizes the findings of the community as described in the report. RECENT PROGRESS Over the past two to three decades, research accomplishments by individuals and groups have led to major advances in understanding chemical processes in the ocean. These advances deal with processes ranging in scale from molecules to ocean basins. This chemical perspective has provided critical information and insight to many central oceanographic questions as well as to issues in the companion fields of biological, physical, and geological oceanography. It has also spun off many chemical tools with which other fields could make their own progress. The FOCUS report assesses this headway in detail. Progress Reports, written by experts in the various fields of ocean chemistry, highlight these significant research accomplishments in ten areas: biogeochemical cycles, oceanic sources and sinks, gases, ocean paleochemistry, physical chemistry of seawater, sedimentary processes, organic matter, anthropogenic effects on the oceans, chemical tracers of ocean ventilation, and chemical analyses and approaches. Among the many advances during this period are: learning most of what we now know about internal cycling of materials within the ocean, such as vertical and horizontal fluxes. Previously, we had only basic understanding of chemical fluxes between the oceans and neighboring Earth compartments (e.g., land, sediments, atmosphere). New sub-fields have been developed, addressing areas such 1 Excerpted and adapted from The Future of Ocean Chemistry in the U.S.: Report of a Workshop. http://www.joss.ucar.edu/joss-psg/project/oce-workshop/focus. The FOCUS committee was co-chaired by Ellen Druffel and Lawrence Mayer. Its members are Lawrence Mayer (University of Maine), Ellen Druffel (University of California, Irvine), Cindy Lee (State University of New York, Stony Brook), Michael Bender (Princeton University), Ed Boyle (Massachusetts Institute of Technology), Richard Jahnke (Skidaway Institute of Oceanography), William Jenkins (Woods Hole Oceanographic Institution), George Luther (University of Delaware), and Willard Moore (University of California). Cindy Lee presented a summary of the FOCUS activity at the symposium.
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50 Years of Ocean Discovery: National Science Foundation 1950—2000 as photochemistry, vertical particle flux and scavenging, and organic complexation of metals. producing trustworthy measurements of concentrations of most of the elements in seawater and realizing that the concentrations generally followed patterns that are predictable based on a combination of elemental chemistry, biological processes, and global water circulation patterns. Previously we had either zero or erroneous values for concentrations of a majority of the elements in the ocean. uncovering the relationships between biological processing and chemical diagenesis in sediments, critical to areas such as the coupling of water column and sediment processes, mineral formation, and paleoceanographic interpretations. assessing the crucial role that hydrothermal processes play in chemical budgets of the oceans, as well as the role of chemical processes in the very dynamic biological and geological phenomena found in rift zones. determining the importance of coastal margins as locations of very high productivity, high carbon flux, and high sedimentary carbon storage as compared to the rest of the open ocean. FUTURE RESEARCH TRAJECTORIES We used our review of past progress and our sense of impending issues to guess at the future of the science. Our time horizon forward is on the order of two decades, roughly that used for our backward look. Forecasting progress in a field as broad as ocean chemistry requires that we break it into smaller chunks amenable to handling. Organizing this effort along the lines of our review of progress, however, allows the past to rule the future. To avoid the smaller tribalisms that exist in our (or any) field, it was necessary to keep the participants from breaking into their natural caucuses. We needed a means to shake up the traditional thinking patterns. We therefore chose to divide oceanic processes (not necessarily chemical processes) along the lines of the time scales within which their characteristic patterns emerge. We focused on processes occurring at (1) seasonal and shorter time scales, (2) seasonal to annual time scales, (3) annual to millennial time scales and (4) greater than millennial time scales. Of course, this choice forces its own structure onto the field, so we also considered possible omissions and overlaps. This time-scale approach reinforces the role of ocean chemistry in the solution of a variety of interdisciplinary oceanic problems. Synthesizing questions raised using the time-scale approach required identification of major themes that the field of ocean chemistry will address over the next few decades. We attempted to balance a desire to identify exciting problems, apparent at this time, with the need to provide umbrellas likely to contain the unexpected discoveries of coming decades. The results of our deliberations can be grouped into eight themes. Major and minor plant nutrients—how they are transported to the euphotic zone and affect community structure, and how these processes are influenced by natural and anthropogenic changes. The ocean's ability to support life and the role of life in maintaining the chemical constitution of the ocean are strongly affected by the transport and redistribution of nutrients. Despite exciting progress over many decades, it is clear that unknown processes are controlling the patterns of these mutual controls. Rapid progress will show how subtleties in nutrient dynamics affect end states of great importance, such as fisheries and harmful algal blooms. Land-sea exchange at the ocean margins. Margins influence biogeochemical cycles to an extent much more than their areal extent might imply, while being especially susceptible to anthropogenic influence. Processes that occur disproportionately in margin environments, such as organic matter burial, mineral formation, and denitrification affect the oceanic balances of many elements. Unraveling the highly variable complex of chemical, physical, geological, and biological linkages in margins will provide needed context for human colonization of the coastline. Organic matter assemblies, at molecular to supra-molecular scales, their reactivity and interactions with other materials. Organic matter must be characterized at scales including, but also greater than, its molecular constituents, to enable understanding its preservation, transport, and interactions with inorganic materials. The "micro-architecture" with which constituents are assembled controls reactivity with important implications for primary and secondary production, photochemical processes, mineral formation, and trace metal dynamics. Advective chemical transport through the ocean ridge system (ridges and flanks), ocean margin sediments, and coastal aquifers. Fluid flow through these environments appears to have greater importance than previously appreciated, and may strongly influence many oceanic chemical cycles. Greater understanding of the magnitude and variability of these advective transports will improve budgeting of chemicals in the ocean and provide explanations for many regional processes affected by the flow, such as mineral formation and nutrient inputs. Forecasting and characterization of anthropogenic changes in ocean chemistry: consequences at local and global scales. Climatic as well as chemical changes to the oceans will affect many different biogeochemical cycles. Assessing natural variability will be critical to determination of anthropogenic effects. Linkage to other oceanographic variables, such as biological and physical processes, will enable better assessment of the role of the oceans in global environmental change. Air-sea exchange rates of gases that directly influ
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50 Years of Ocean Discovery: National Science Foundation 1950—2000 ence global ecosystems. Carbon dioxide and other greenhouse gases, halocarbons that affect stratospheric ozone, and sulfur gases that create sulfate aerosol all have important source and/or sink terms in the oceans. More accurate determination of air-sea fluxes of these gases, of both natural and anthropogenic origin, are critical to assess processes affected by these gases. Relationships among photosynthesis, internal cycling, and material export from the upper water column. Most production and remineralization of organic matter occurs in the shallow euphotic zone. Our understanding of processes such as CO2 and N2 sequestration from the atmosphere and pelagic-benthic coupling are thus critically dependent on improving our understanding of euphotic zone recycling. Controls on the accumulation of sedimentary phases and their chemical and isotopic compositions. Further development of paleoenvironmental indicators will enable better understanding of past climatic and carbon cycle variations. Earth historical records provide an invaluable guide to natural variability of the chemistry/climate system, including natural "experiments" in which the whole system has responded to a perturbation. Synthesizing these eight topics, three major areas appear especially fertile for future discovery. The first is boundary interactions between major reservoirs, including gas exchange between air and sea and advective flows through ridge systems and coastal aquifers, which promise resolution of important mass balances for the surface of the Earth. The second area where we are on the verge of making sizable discoveries is the ocean's ability to support life, its effect on the cycling of elements in the upper ocean, and the forms of organic matter that fuel various life forms. Last, and perhaps most important are the links between environmental changes (e.g., anthropogenically induced impacts) and the chemistry of the ocean—links that have both local and global significance. RESEARCH INFRASTRUCTURE Future advances in ocean chemistry will require new approaches to infrastructure to support the science. Emerging technologies, and access to them, will be critical for the next advances. These include methods to sample, analyze, and visualize chemical distributions in the oceans at vastly wider ranges of time and space scales than heretofore possible. As we focus more strongly on variability in the ocean, higher data densities over longer time scales will be required. Sensor technology that can be used at sea is particularly well-poised to enable new insights into the functioning of the oceans. There is need for some tuning in the funding approaches to certain kinds of research, such as new opportunities for mid-size research groups or long-time series. Shifts in approach to recruitment, training, and career guidance are needed to provide the human resources for growth of this field. Because ocean chemistry is among the most interdisciplinary of marine sciences, greater linkage is recommended to other oceanographic and materials science disciplines. For example, shifts in training from chemical to oceanographic programs must not lead to atrophy of our connections to the chemical sciences. Examples of such connections include more active recruiting of chemistry undergraduates and involvement of ocean chemists in their environmental science program areas. CONCLUSION The picture that emerges from this self-assessment is one of a field with a record of impressive recent gains and a prospect of imminent further advance. These advances should benefit not only the field of ocean chemistry narrowly defined, but will be central to a variety of other fields of Earth science.
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